Electric switch



Oct. 19, 1937. F. FARRELL ELECTRIC SWITCH Filed Oct. 15, 1935 4Sheets-Sheet l Imfen qr Fwd ZZIrrel/ a 2% .71. jam

Oct. 19, 1937.

Filed 'Oct. 15, 1935 4 Sheets-Sheet 2 7 r 0 0/ 6 M a w W m w w m m% 5 7T m? 9 W v. 2 w mm F. FARRELL ELECTRIC SWITCH Oct. 19, 1937.

4 Sheets-Sheet 5 Filed Oct. 15, 1935 77 2a Eire/j i 'rngy Oct. 19, 1937.HR E 2,096,033

ELECTRIC SWITCH Filed 001:. 1935 4 Sheets-sheaf 4 I Ira/21x13? 7 /190ZZZI'IPZ/ Patented Oct. 19, 1937 UNITED STATES PATENT OFFICE ElectricalEngineers E corporation of Illinois quipment Company, a

Application October 15, 1935, Serial No. 45,113

6 Claims.

The present invention relates to electric switches and has for itsgeneral object the production of an electric switch which shall beefficient and satisfactory in operation while being simple inconstruction, economical to manufacture, and of such design as to occupya minimum of space relative to its electrical capacity.

More specifically, one object of the invention is to provide a switchwherein spring means are employed to apply heavy pressure to the switchcontacts when contacting, and simultaneously therewith to hold theactuating mechanism in holding position.

Another object is to so construct and arrange the switch contacts thatthey will, when engaged, provide a novel application of balanced forcesto thereby give the high contact pressure desired.

Another object is to construct the spring means by which the differenttoggle and contacting functions are performed, in a novel way such as toprovide indications of the pressures upon the contacts, which are beingexerted at any given time.

Another object is to utilize the spring means as couplings between thefixed and movable parts in such a way as to provide a floatingconstruction for the movable parts and then to employ self-centeringcontacts, the two cooperating in the centering of the parts when theswitch is moved into closed contact engaging position.

Another object is to so construct the main contacts of the switch thatthey will be related to each other somewhat after the manner of a balland socket, whenever in engagement. By so doing there will be efiicientengagement whenever the switch is closed even though the contacts maynot be in true axial alinement. Akin to this plug and socket, or balland socket, feature, is that of providing substantially a line contact,50- called, between the engaging contact surfaces of these ball andsocket members in all the different positions they may occupy when incircuit closing position.

Still another object is to combine these various features in a structurewherein telescoping insulating tubes inclose the different switchcontacts.

In this connection it may be pointed out, however, that the variousfeatures of the invention may be combined in various ways and still comewithin the scope of the invention. Thus, for example, the earlierobjects may be attained without employing the particular insulationprovided by telescoping insulating tubes.

Besides the various objects recited, other objects will appear as theinvention is more fully set forth. To this end reference should be hadto the following detailed description taken in connection with theaccompanying drawings, while the scope of the invention will be moreparticularly set forth in the appended claims.

Before considering the drawings, it may be pointed out that bytelescoping the switch contacts and by providing a plurality of linecontacts for each pair of mating contacts, considerable saving of spacefor the switch structure may be obtained. Thus if a total length of linecontact is required in any specific case to handle the energy of thecircuit, then this length may be divided up among two or more sets ofcooper ating contact surfaces and these sets may be arranged laterallyof the aXis of the telescoping contacts with a great saving in space inthe length of the contacts. A specific example is a sort of ball andsocket structure wherein a pluglikering enters between two rows ofspring fingers. The total length of required contact is here dividedinto two lengths, one provided by the outer surface of the ring engagingthe outer spring fingers and the other by the inner surface of the ringengaging the inner spring fingers. This is one specific form of contactsherein disclosed. Obviously, the total length might be divided into morethan two parts. The disclosed embodiment, however, illustrates the idea,which constitutes an important feature of the present invention.

It should also be noted that the contact arrangement mentioned providesa self-centering action and that by giving the meeting contact surfaces2. suitable curvature, there may be considerable shifting of thecontacts relative to their longitudinal alinement without decreasing theefficiency of the contact engagement as a conductor of electricity. Theaction of the engaging contacts is to a limited extent like that of auniversal joint. The movements take place without the loss of efficiencyin electrical conductivity through the joint.

Referring now to the drawings, Fig. l a front elevation of a three-phaseswitch constructed and arranged in accordance with the presentinvention, certain portions being cut away to show details ofconstruction; Fig. 2 is an end elevation of the same, the view beingtaken from the right in Fig. 1 and showing the contacts in closedposition; Fig. 3 is a similar view, with certain parts removed and otherparts in section, illustrating the contacts in open position; Fig. 4 isa sectional plan view of a portion of the structure, the plane ofsection being indicated by the line 4.-4 of Fig. 2; Figs. 5 and 6 aredetail views illustrating a stop employed in conjunction with the togglemechanism; Fig. 7 is a vertical section through the switch parts of onephase, the plane of section being indicated by the lines 'i l of Fig. 1;Fig. 8 is a section of a portion of the toggle system, the section beingtaken along the arcuate section indicating line 8-8 of Fig. 2; Fig. 9 isa. vertical section illustrating one of the spring couplings by whichthe bridging contact lar sectional view illustrating a modified springcoupling; Fig. 13 is a similar view illustrating a further modifiedspring coupling; and. Fig. 14 is a similar View illustrating a thirdmodified coupling.

Throughout these views like characters refer to like parts.

'As previously indicated, in the present'case a three-phase switch isshown. In brief, the same comprises a. main frame A, a shiftable frameB, and three contact carrying frames C, one for each phase, said framesC being connected to the frame B by three sets of spring couplings D.The result is that each frame C is yi-eldingly mounted upon theshiftable frame B. For each phase there is an upper insulator E, a lowerinsulator F, and any intermediate insulator G, telescopically arranged.The insulators E and F are both mounted on the frame A while the centerinsulated member G is mounted on the appropriate frame C. Associatedwith each set of insulators E, F, G, are corresponding contacts, H, Jand K. A toggle system L serves to raise and lower the frame B togetherwith all the parts carried by it. In open circuit position the contactsH and K are separated, while in closed circuit position they are in firmcontact with each other, as clearly shown in Fig. '7.

The main frame A may be variously constructed but in the present caseincludes two flanged end frames 2i! united by upper angle bars 2| andlower angle bars 22. These bars are secured to the end frames in anysuitable way as by means of bolts and nuts 23, 24, the former serving toconnect the upper bars 2| and the latter the lower bars 22.

The end frames 23 are provided in their flanges with openings 25 throughwhich securing bolts or the like may be passed into a suitable panel orother support, as will be obvious.

The frame B which is the shiftable frame of the structure, comprisesangle bars 26 which extend along the front and rear of the structure ina manner similar to the bars 2|, 22 of the frame A and are connected attheir ends to end frames 2'i. The latter are provided with horizontalflanges 28 which overlie the horizontal flanges of the angle bars 26 andare secured thereto by bolts 29 or the like. The latter are providedwith nuts as usual and the parts of the frame are thus firmly securedtogether. In its up and down travel the frame B is guided by guide rods32 which are firmly secured to the frame A. Connection is made bypassing the rods through openings in the horizontal flanges near thetops and bottoms of the end members 20 and securing the same in place bysuitable nuts 33 threaded on to the ends of the rods and screwed homeagainst the flanges. The end members 21 of the shiftable frame B haveguiding sleeves 4| through which the rods 32 extend. These sleeves areof considerable length and have a sliding fit on the rods. Hence aguided up and down movement is provided for the frame B in its operativetravels.

The frames A and B are common to the three sets of insulators and theirassociated contacts.

When it comes to the frames C, we have one frame for each set ofinsulators and contacts. Each frame C thus constitutes a mounting forthe intermediate insulator G and its associated bridging contact K, ormodification of that contact. Each frame C takes the form of a webhaving an upstanding flange 3|. The latter has an outline conforming tothe periphery of the insulator G which, in the present case, iscircular. The horizontal web portion 3% is apertured near its fourcorners for the passage of the bolts of the coupling devices D. Thelatter provide the yielding connections between the shiftable frame Band the mounting plates or members C of the different phases. Viewedinanother way, each flange 3! is a supporting frame which embraces theinsulator G and the portions of the web 30 which extend outward from theframe 3| and contain the apertures for the retaining bolts of thecoupling devices D, are lateral projections.

Turning now to a consideration of these coupling devices, We find thesame may take quite different forms. The preferred form is thatillustrated in the earlier figures of the drawings, and more in detailin Figs. 9, l0 and 11. In each of these couplings there is a centralbolt 34 which is threaded into an opening in the horizontal web of theangle bar 25 of the shiftable frame B. Upon this same bolt 34 is aflanged sleeved member 35 which has the interior of its sleeve 36threaded for engagement with the threads of the bolt 34 and at its lowerend is provided with the horizontal flange 3?. By rotating the member35, the same may be adjusted lengthwise of the bolt 3 The flange 3?forms a seat for the lower end of a coiled compression spring 38. Theupper end of the spring bears against a flanged member 39 which has theouter surface of its sleeve til threaded through an opening in the web38 of the associated contact-carrying member C. The flanged member 39moves freely up and down over the member 35 and obviously carries withit the engaged portion of the Web 36. The member 39 is given an upwardlimiting position by means of a nut 52 which is likewise threaded uponthe upper end of the bolt 3%. By adjusting the nut upon the bolt 3d, theposition of the member as may be adjusted to give more or lesscompression to the spring 38. As clearly shown, the interior of the nut42 is cut back on its under side, as indicated at 53, to enable theskirt of the nut to pass down over the exterior of the sleeve 36 of themember 85.

In Fig. 9 the parts are shown in the position they would occupy whenfirst assembled and before any compression is given to the spring 38. Itwill be noted that the upper end of the bolt 34 is also provided with anextension 4 3 which passes out through an opening in the head of the nut42. As clearly shown, this extension is provided with scale markings 45.are in the position illustrated in Fig. 9, the top of the projection 4%is flush with the top of the nut H2 and the markings 45 are intheir zeroposition.

Whenever the nut 42 is screwed down upon the bolt as so as to force theflanged member 39 downward to place the spring 38 under compression,then the parts assume some such position as illustrated in Fig. 10. Itwill be noted that in such case the projection id extends beyond the nut42 and by reading that marking 35 which When the parts Lil Cal

her 39,

2,096,033 comes nearest to the top of the nut it will be pos sible toknow from inspection the amount of compression which is given to thespring. Thus, indicating means are provided for knowing at once the setcompression.

When the switch mechanism is assembled, the four springs 38 associatedwith each contact carrying member C are given preferably the same degreeof compression. It will be seen that if each spring be given acompression of, say, 75 pounds, then the total of the four springs wouldbe 300 pounds for the particular member C and its associated contact.

It will be apparent from what has been said that if the member B beforced upward by the toggle mechanism L, which constitutes the operatingmechanism of the switch, then the different members C would be carriedupward as a unit until some resistance was encountered to cause thesprings to be compressed still further. As we shall see later, thisoccurs when the reciprocating bridging contacts carried by the frames Cmeet and effectively engage the upper terminal contacts of the switch.

When the switch parts are brought into final position, then the springs38 are compressed beyond the amount at which they have been initiallyset and they assume some such position as illustrated in Fig. 11. Therethe parts are shown in a position corresponding to the fully 'closedposition of the switch. In changing from the position of Fig. to theposition of Fig. 11, the projection 44 will not be changed but it willbe noted that the nut 42 will pass upward out of engagement with themember 39. The extent of this movement will show upon each couplingdevice that there is a pressure applied to the contacts in excess ofthat given the springs as an initial set. For the purpose of measuringthe extent of this additional pressure, the exterior of the sleeve 36 ispreferably provided with scale markings 46. By reading down upon thesemarkings, a measured value for the extent of pressure applied by eachcoupling device D may be observed. If desired, these markings 46, andalso the markings 45, may be carefully graduated to indicate thepressure in pounds or other convenient unit. Thus, indicating means forknowing the extent of contact pressure in addition to the setcompression is provided.

Under the assumption, namely 75 pounds per spring, it will be apparentthat as soon as any of the markings 46 appear by reason of theseparation of the nut 42 from the sleeve 40 of the memthen more than 300pounds pressure is being applied between the central contact and theupper contact, such being in the case of Fig. 7, the contacts K and H.

While on the subject of these spring coupling devices, it might be wellto point out that the structure of the preferred spring means D may bemodified and the modifications may be extended to include a very simpleform.

Thus, in the case of the coupling D, shown in Fig. 12, the structure isthe same as shown in Figs. 9, 10 and 11 except that the flanged member39 is omitted and the upper end of the spring 38 acts directly againstthe under side of the web of the member C. Obviously, where the member39 is employed, it is possible to adjust the position of the member Cwith respect to the flange of the member 39, and thus relativelyposition the frames B and C, without in any way changing the initial'set given to the spring 38. Of course where the member 39 isomitted-this ad- However, in many not be desired. In

justment is not possible. cases this adjustment may the case of thecoupling D, there are the same scale markings 45.and 46 and they servein the same way exceptthat the reading of the markings 46 indicates theseparation between the nut 42 and the web 30, instead of between the nutand the sleeve 40 of the member 39, as in the preferred form. Theactions of the parts when pressure in excess of the set amount isapplied are just the same .as before.

In the case of the modified coupling D we have advanced one more steptoward simplification, with a resultant omission of function. In thiscase, the nut 42 is replaced by the nut 48, and the bolt 34 gives placeto a similar bolt 49, which is threaded, as before, into the flange 26of the ad- J'acent member 26 of the frame B, and which, as before,carries the flanged sleeve member 35. In

this case, the spring 38 is compressed between the flange 37 of themember the web 3|] of the frame C. By reason of substituting the bolt 49for the bolt 34, there are nomarkings 45 to indicate the extent ofinitial set given to the spring 38. markings 46 which will indicate theextent of separation between the lower surface of the nut 48 and theupper surface of the web 30. The extent of separation as indicated bythis reading, will show the amount of compression in to the set amount,that is being applied through that particular coupling to the associatedcontacts.

Going still further in the direction of simplifi- 35 and the under sideof cation, we have the coupling structure D wherein the central bolt 50has a head 51 at its lower end which bears against the under face of theflange 26 of the member B. A nut 52 is threaded on the upper end of thebolt 59 and is pressed home against a sleeve 53 which presses at itslower end against the upper face of the flange 26 and its upper endagainst the under face of the nut 52. When the nut is screwed down tightupon thebolt, then the parts 26, 56, 52 and 53 move together as a unit,and so long as the resistance to the movement of the frame does notexceed the amount of the set compression in the spring 38, said memberwill also move with the other parts. But, as soon as the resistance tothe applied pressure is greater than said amount, the spring will beginto compress and the frame members B and C will be brought nearertogether. In this case, scale markings 46 on the sleeve 53 may serve toindicate the amount of extra compression being applied through theassociated spring.

Such markings will measure the extent of separation between the underface of the nut 52 and the upper face of the web 30 of the frame C.

These various forms of couplings maintain a loose connection between theframe B on the one hand and the several insulator and contact bearingframes C on the other hand. As a result, the mountings for the bridgingcontacts have a floating movement upon, or relative to, the frame B andin consequence thereof the contacts readily adjust themselves to eachother forgood engagement.

It will also be noted that when. the operating frames C are moved intothe closed position, and when the pressure in the springs exceeds theset amount, say '75 pounds per spring (300 pounds per phase), then thesprings shift further, as before pointed out, and there is still reserveenergy stored in the springs and available to compensate for anyyielding which may occur by reason of the There are, however, 7

addition 7 parts remaining under pressure over along period of time orby reason of wear of the parts.

As previously indicated, there are three tubular telescoping insulators.The uppermost of these is the insulator E. It is the one of largestdiameter and includes a skirt 56 and an apertured end iii. The outersurface of the insulator is corrugated to increase the exterior creepingsurface. Near its lower end it is connected to a mounting member 54having a vertical annular flange 55 and a web 58, said member beingsimilar in shape and outline to the intermediate mounting member C,previously described. The four corners of the web 58 are apertured, asshown more particularly in Fig. 4, and suitable bolts 59 pass throughthese apertures and mating apertures in the horizontal flanges of themain frame members 21 and are provided with appropriate nuts. Byscrewing the latter home, themounting 5d of each insulator E may befirmly and fixedly secured. Suitable cement 65 positioned between theinsulator and the flange 55 holds the insulator in place upon the mainframe A.

The insulators F at the lower portion of the switch are similar to theinsulators E but of considerably smaller diameter. Each such insulatorcomprises a skirt 6i and an apertured head Eil The outer surface of thisinsulator is also corrugated near its lower end so as to increase thecreepage surface. Connection is made between each of these insulatorsand the lower members of the frame A through a member 62 similar inshape to the member 5%. The web portion of the member 62 is connected toflanges of the frame members 22 by suitable bolts 63 having appropriatenuts. In this instance cement 64 binds the insulator to the annularflange of the member 62 and the insulator is thus held firmly in placeby attachment to the lower portion of the main frame A.

The intermediate insulators G are similarly secured by cement 65 to thevertical flanges 3i forming part of the intermediate frames C. Theinsulators G thus move with the frames C. As clearly shown, each ofthese insulators is of intermediate diameter and passes inwardly of theassociated insulator E and outwardly of the associated insulator F. Eachinsulator G is also provided with an inwardly projecting flange 65 whichserves as part of the connection with its contact K as hereinafter morefully pointed out.

When it comes to the contacts which are carried within these differentinsulators, different contact arrangement may be employed. In thepreferred form of the invention, each of the terminal contacts I-Icomprises a block 68 of copper or other good electric conductingmaterial, which has a threaded shank 69 on the one side and a series ofinner spring fingers l0 and outer spring fingers ii on the other side.The shank extends upward through the aperture in the head 51 of theinsulator E and is firmly secured to the insulator by a nut '52,suitable washers l3, 14 being employed to perfect the connection. Anadditional nut 75 is threaded on the shank 69 and serves as a binder forthe electric conductor that is connected to the shank. The fingers l0and H are preferably provided by cutting away the block 68 so as toprovide a central space 16 and an annular space ll and then splittingthe resulting projections by 1ongitudinal cuts so as to give the severalfingers, viz., the fingers ill on the inside and the fingers ll on theoutside. These are also preferably curved so as to provide abell-mouthed approach, as clearly illustrated in Fig. 7. A coiled outerspring 18 extends around the outer fingers H and tends to force theminward. A somewhat differently coiled spring 19 extends spirally aroundwithin the space '16 and engages the inner surfaces of the inner fingers10 and by its action tends to force these fingers'outward. The springpressed fingers l0 and H, however, are sufiiciently stiff, while yetlaterally yielding, to provide the requisite space Tl for the entranceof the cooperating ring contact 95. Thus, a contact having a solid baseportion and twoconcentric rows of contact fingers is provided. Thespring fingers l0 and II cooperate with the space Tl between theirrespective rows to provide a socket for reception of the plug-likeportion upon the associated bridging contact, presently to be described.

In the embodiment under consideration, each of the lower terminalcontacts J is in the form of a rod 82 threaded at its lower portion andprovided with retaining nuts 83, 8d, the former acting on the inside ofthe head St of the insulator F and the latter operating on the outside.Suitable washers 85, 86 are positioned between the nut 83 and the head 6l on the one hand and the nut 85 and the head iii on the other hand. Theextra nut 87 serves to bind the conductor, in whatever form it may be,to the terminal contact J. The latter is preferably composed of copperor other good conducting material.

Each of the intermediate contacts K is composed in this embodiment of atube 88 which is reduced in diameter at an intermediate point and splitso as to provide a series of spring fingers 89. The reduced diameterenables the spring fingers 89 to fit upon and make good contact with thelower terminal J. A series of coiled springs 96 surround the springfingers 89 and press them inward against the surface of the rod 32 ofthe contact J. With this construction the tube 88 may be moved up anddown upon the rod 82 and in all positions there will be good electricalengagement between the contacts.

The upper portion of the tube 89 is exteriorly threaded so as to bescrewed into a contact head 91. The latter is provided with a lateralflange 92 and an auxiliary clamping ring 93. Between the flange 92 andthe ring 83 is positioned the insulator flange 65. The ring 93 hasthreaded engagement with the outer portion of the head 9i and byscrewing the ring 93 home against the flange 65, the head 91 and thetube 88, which is connected with it, are firmly secured to theintermediate insulator G. If desired, intervening washers 9d may beemployed upon the upper and lower faces of the flange 85 in order toimprove the mechanical connection. The upper part of the head 9! isshaped so as to provide a contact ring 95 which is solid and incross-section has tapered surfaces similar to the surfaces of a geartooth. This ring is adapted to pass into the annular space Tl betweenthe spring contact fingers l9 and "H of the upper contact H. The ring 95thus acts as a plug and the space H and the associated fingers i6 and Hcooperate to provide a socket for receiving theplug-like portion 95.

The inclined bell-shaped walls of the socketlike space ll cooperate withthe inclined walls of the plug-like ring contact 95 to provide aselfcentering action of the contacts. This action is permissible becauseof the loose mounting of the associated frame C upon the frame B'throughthe spring coupling means D, as before pointed out.

Besides obtaining the self-centering action, the engaging surfaces ofthe ring 95 and fingers l0 and H are such that a line contact isprovided gr H on each side of the'ring when the switchis in closedposition. Not only is this true, but it is. also true that such a linecontact willexist even though the bridging contact be out ofexact axialalinement with the upper contact. In this way a certain floating of thebridging contact is possible without destroying the line engagement ofthe contact surfaces. One pair of lines, an. inner and an outer, willexist for each position of the parts, ranging from the central positionwhere the axis of the intermediate contact isin exact alinementwith theaxis of the upper contact, on through intermediate positions in allpossible vertical planes, to the extreme positions in said planeswherein the axes of the two contacts intersect at the maximum possibleangle.

Again, in these several positions of the contacts, the pressure exertedupon the ring contact 95 by the associated contact fingers l and II willbe approximately equal and relatively high, the total pressure beingdivided among the several fingers. The pressures provided by theresiliency of the fingers i0 and II reinforced by the action of thesprings 1'8 and 79 cooperate with the action of the springs 38 of thecouplings D to maintain the contacts in proper position and thus insurethe high pressure between the conducting parts while the switch is inclosed position. In practice the contacts may be so firmly pressedtogether that the conductor formed thereby is in electrical effectpractically a continuous solid conductor. Pressures upon the contactparts in excess of that required to produce this result need not beapplied. By maintaining these high pressures for all line 1 contactsbetween the two conducting contacts,

there is no weakening of the conducting capacity even though exactalinement be not maintained. In this wayan eflicient and long livedswitch is provided. The material of the tubular conducting member K isalso copper or other good conducting metal.

In considering this matter tween switch parts, we find the centralpluglike contact 95 and the associated spring finger contacts I53 and Hgood exampes. Thus, the outer surface of the ring 55 contacts with theinner surfaces of the several spring fingers H. Because of the curvatureof the contacting surfaces of of these parts, clearly shownin Fig. 7, itfollows that the portions of the surfaces thus engaging each other arein a practi'cally continuous line around the outside of the ring $5.This line-like engagement is what is meant by a line contact, althoughunder pres-' of line contacts besure there might be some deformation ofthe parts along the contact line and thus the line might haveinfinitesimal width and so be a zone of infinitesimal wid h. The termline contact however is commonly used to describe this sort ofengagement between switch'contacts. Similarly. because of the curvaturesof the inner face of the ring and the outer surfaces of the fingersthere is a similar line contact extending around on the inside of thering and the outside of the spring fingers Iii. In this case, the sum ofthe lengths of these two line contacts determines the carrying capacityof the switch, as

before indicated.

The mechanism for moving the shifting frame B upward and downward is.found in the toggle mechanism L. This mechanism, or toggle leversystemas it may be called, applies the requisite high pressure to the engagingsurfaces of the contacts K and H when the switch is in fully closedposition. Such mechanism includes a longitudinalshaft 98 suitablyjournaled in the main frame A, crank arms 99 keyed to the opposite endsof the shaft 98, and cooperating links I00 acting between the ends ofthe crank arms 99 and the end members 2'? of the frame B, the connectionwith the latter being provided through suitablepivots I 0|. Theconstruction is such that the members 99 and Edi] act as toggles, one ateach end'of the switch s'ructure. The toggle arrangement is such thatthe central pivots I02 by which the arms 99 and links are connected movethrough and slightly beyond a dead center point existing between thecenters of the shaft 98 and the pivots MI. The movement of the togglemembers to this overenter point brings the contacts H and K into therequisite firm engagement, as aforesaid, and then the toggles lock theswitch parts in closed position. In order to properly bring about thisstaying of the toggle movement each end member 2'! is preferablyprovided with a stop The stop I03 may take different forms butpreferably an eccentric cam Hit is employed as illustrated moreparticularly in Fig. 6. This cam I04 may be held in any desired positionby clamping it against the face of the adjacent member 21 by anysuitable means, as, for example, the bolt I05. Where the latter is used,its head may press against the cam I5 4 and it may be held in permanentengagement by means of a nut I06 on the opposite side of the framemember 27, all as illustrated more particularly in Fig. 5.

Obviously, the actuating shaft may be rotated through the requisiteangle in order to bring about proper opening and closing movements ofthe switch contacts by any suitable means. In the present instance, alever 50 is keyed to one end of the shaft 98 in a position adjacent toone of the end members 2.? of the main frame A. This lever has a handleI It at its outer end by which an operator may move it to and frobetween the closed position, illustrated in Fig. 2, and the openposition, wherein the lever extends downward and forward from the shaft93. The lever I09 is preferably provided with lugs Hi which areapertured and made to lie adjacent to a similarly apertured portion ofthe main frame, such as indicated at IE2, near the lower end of themember I I3, which is secured by bolts H4 to the adjacent portion of themain frame A, suitable spacing sleeves I55 surrounding the bolts andproperly spacing the bracket member H3 from the end frame member 20.When in proper position the lever 05 may be held against interference bya padlock H5 which may have its hasp passed through alined openings inthe lever I08 and the lugs H2 of the frame H3, either in the open orclosed position of the switch, as desired.

The frame I I3 is provided with a grooved channel H8 which extends in anarouate path and provides a pathway for a retaining pin H9 carried bythe lever I03. This is clearly illustrated in Fig. 8 which is a sectionalong said arcuate pathway. A leaf spring I20 is secured at one end bypins I20 to the face of the lever I as and the pin H9 is secured to thefree end of the spring I20 so that the same may be yieldingly moved withreference to the lever. A button I2! on the free end of the spring I20and preferably in alinement with the pin H9 serves to draw the pin H9out of one of two recesses I22 which it may occupy at the ends of itstraverse. The

l and arrangement may lever' M39 is suitably recessed at l23' to providefor them and out movement of the pin H9.

From what has been said it will be clear that the various springs 38 ofthe coupling devices D serve two functions. One of these is to providethe requisite pressures between the electrical switch contacts, as, forexample, contacts H and K, and the other is to hold the toggles in theirlocking positions after they have been moved to their holding positionsbeyond dead center, corresponding to the closed position of the switch.As previously indicated, the contact structure be considerably modified.What has been described in detail heretofore has included a solid lowercontact and a tubular intermediate contact. In respect to modificationsof these contacts it is clear that the shapes or the coacting contactsurfaces may be greatly varied over those shown and still get the balland socket action and the requisite line contacts and line contactlengths for the different positions of the engaged contacts relative toeach other. The different shapes of the contacting portions of thecooperating contacts will be determined by the required current carryingcapacity of the switch and other characteristics, such as the shape ofthe insulators required to permit the proper movements of the variousswitch parts and the like.

Obviously, then, in carrying out my invention many alterations andmodifications may be made in the disclosed structure without departingfrom the spirit and scope of the invention. I therefore aim to cover bythe terms of the appended claims all those alterations and modificationswhich rightly come within the scope of my invention.

I claim:

1. In an electric switch, cooperating electrical contacts, a relativelyfixed insulating mounting for one of said contacts, a relatively movableinsulating mounting for the other of said contacts, actuating mechanismfor said movable mcunting, a set of compression springs acting betweensaid actuating mechanism and said movable mounting to press saidcontacts together when brought into engagement, means for giving saidsprings a variable adjustment to suitably adjust the same with .a givencompression whereby the movement of said actuating mechanism willcompress said springs beyond said given compression only when thepressure between said contacts exceeds an amount corresponding to saidgiven spring compression, and indicating means associated with each ofsaid springs to show the extent of pressure being applied therethroughin excess of said given amount.

2. In an electric switch, cooperating electrical contacts, a relativelyfixed insulating mounting for one of said contacts, a relatively movableinsulating mounting for the other of said contacts, actuating mechanismfor said movable mounting, a set of compression springs acting betweensaid actuating mechanism and said movable mounting to press saidcontacts together when brought into engagement, means for adjusting theabutting ends of said springs relative to both said actuating mechanism.and said movable mounting, thereby to give said springs a setcompression, and indicating means associated with each of said springsto indicate the pressure being applied the-rethrough in excess of saidset amount.

3. In an electric switch, relatively fixed and movable suitablyinsulated contacts, suitable mountings for. said contacts, actuatingmechanism for shifting said movable contact and mounting, a set ofcoiled compression springs each acting between said movable contactmounting and said mechanism, said movable contact and mechanism servingas abutment members for the spring, a bolt-like member secured at oneend to one of said abutment members and movable freely through anopening in the other of said abutment members, a nut secured to the freeend of said bolt-like member and serving through the interveningabutment member to limit its movement away from said spring, and meansfor limiting the inward movement of said nut on said bolt-like member tocompress said spring with a given compression.

4. In a device of the class described, a contact carrying member, anactuating member for said carrying member, a plurality of springmountings carried by one of said members and operating to transmitmotion from one to .the other of said members, each said spring mountingcomprising a coiled compression spring, a holding bolt secured to one ofsaid members and passing freely through an opening in the other of saidmembers, a nut on the free end of said bolt for limiting the movement ofthe adjacent member away from said spring and cooperating with saidadjacent member to give said spring a definite set compression, andscale markings on said bolt for indicating two things, one the setcompression of the spring, and the other the extent of movement of saidmembers relative to each other whenever said spring is compressed beyondsaid set compression.

5. An electric switch comprising relatively fixed and movableself-centering electrical contacts, a movable mounting for saidmovablecontact, said mounting having lateral projections, a movable supportingframe for said mounting having portions adjacent to said projections, aset of spring couplings uniting said projections and frame with yieldingconnections, each coupling including a bolt secured to said frame andextending loosely through an opening in the associated projection, acoiled spring around said bolt, means on said bolt for compressing saidspring with an initial pressure, said couplings being peripherallyspaced about said movable con tact and the springs and loose connectionsthere a" of serving to provide a floating action such as to permit saidcontacts to center themselves when brought together, and means formoving said frame toward and from said fixed contact.

6. An electric switch comprising two end insulating tubes, anintermediate insulating tube in telescopic relation to said end tubes,terminal electric contacts within and mechanically connected to said endinsulating tubes respectively, an intermediate electric contact withinand mechanically connected to said intermediate in sulating tube andoperative to electrically connect and disconnect said terminal contacts,a frame by which said end tubes are supported, an intermediate frame bywhich said intermediate tube is supported, all said tubes being inalinement, a toggle system for moving saidintermediate frame to make andbreak circuit, and spring means operating between said intermediateframe and associated tube to yieldingly hold the toggles of said systemin contact closing position and simultane ously therewith to apply ayielding pressure to the engaged contacts.

- FRED FARRELL.

